Categories from the Catalog cannot be deleted. However, they can be hidden, by removing offers from the Category. In that way, Category will not appear in your Catalog. This option is available only for users with Seller admin rights.
In the picture below you see the category "January" that we will hide in the following steps:
1. In order to hide a category from the Catalog, you have to remove the chosen category (that you want to hide). Select Catalog → Layout for customers:
When opening this page, you will by default see the Products, that are placed in the first of your defined categories. Therefore, you should select "Category" which you want to hide.
2. In the body of the product, you can see all the categories, in which this product is placed. In order to hide the chosen category, select the "Edit Tags" button:
3. Remove name from the category, by clicking the red cross → press "Save":
4. In order to see if the category is hidden, you have to Select Catalog → Products:
5. As you can see in the below picture, the category "January" is no longer visible in the Product Catalog.